Laser lithotripsy is a minimally-invasive procedure that is widely used in remove stones from the urinary tract, including the urethra, bladder, ureters and kidneys. In order to perform laser lithotripsy, an endoscope (such as a cystoscope, ureteroscope or renoscope) is inserted into the urinary tract to the stone location, and an optical fiber is introduced into the working channel of the endoscope. The fiber is pushed forward until it exits the distal opening of the working channel and comes into close proximity with the stone. A laser beam is fired through the fiber onto the stone, causing the stone to absorb the laser beam energy and disintegrate.
If the laser beam is fired while the fiber is still inside the working channel of the endoscope, rather than protruding out of the distal opening, the beam can damage the working channel, as well as surrounding tissues. Various solutions to this problem have been proposed. For example, U.S. Patent Application Publication 2013/0072753 describes a system for preventing inadvertent actuation of a medical device. The system includes an elongate tube having a proximal end, a distal end, and a lumen extending from the proximal end to the distal end. The lumen is configured to receive a medical device having an actuated state and an inactive state. A detection system determines the position of the distal end of the medical device relative to the distal end of the elongate tube and controls the activation of the medical device.